Drill bit sharpening mechanism



March 28, 1944. El. COTTON 2,345,100

DRILL BIT SHARPENING MECHANISM Filed March 16, 1943 2 Sheets-Sheet l Hll 1 i I l i --l r1 /4 EARL Corn/v INVENTOR I ATTORNEY l6 m: EARL ro/v.INVEN R March 28, 1944. E. l. COTTON 2,345,100

, DRILL B IT SHARPENING MECHANISM Filed March 16, 1945 2 Sheets-Sheet 2)8 ATTORNEY Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE Earl 1.Cotton, Lucerne, Wash. Application March 16, 1943, Serial No. 479,322

4 Claims.

This invention relates .to drill bit sharpening mechanism and, moreparticularly, to a sharpening mechanism for dull, detachable drill bits.

While it was conventional in the reshanpening of drill steel having thedrill bit integrally formed on one end thereof by forging means, whensuch conventional steel was displaced by detachable drill bits, thesharpening of such dulled bits has always been accomplished either bygrinding or milling operation, but not by true forging practices. Animportant problem to overcome in resharpening a dull detachable drillbit is the prevention of damage to the usual threaded skirt by which thebit is attached to a drill rod for use. The skirt and the threads formedtherein must not be altered or changed in size and shape in any way, andthis limitation has so far been insurmountable in previous knownattempts to employ forging, since the application of force to thecutting wings or teeth of the drill bit is all too easily applied tothis threaded skirt to its damage or reduced utility.

Having in mind the defects of the prior art, it is an object of myinvention to provide means for reconditioning worn, detachabledrill'bits'by the employment of forging practices in such a way as notto injure or alter the threaded skirt of the drill bit.

Another object of my invention is to provide, in a drill bit shapingmechanism of the type described, a pressure receiving element which willsustain the force applied to the face being reshaped while at the sametime preventing the application of that force to the threaded skirt.

A still further and more specific object of my invention is to provide,in a mechanism of the type described, an element for receiving the forceapplied to the drill bit face which element also serves to extrude thedrill bit when reshaped from the reshaping die.

The foregoing objects and others ancillary thereto I prefer toaccomplish as follows:

According to a preferred embodiment of'my invention, I dispose in theupper portion of a column a female die which has movable thereto andtherefrom a mating male die and the two.

are adapted to be brought together with force to reshape a drill bitplaced in a female die.

Specifically, this column has a longitudinally movable bar which fitsinto the female die to receive the bit being reshaped in a manner torelieve the application of pressure to the threaded skirt of the drillbit. I also include means for longitudinally moving this bar to extrudethe drill bit from the female die. In addition, means.

are provided for supporting this longitudinally movable bar duringperiods when pressure will be applied to it in such a manner that it isdirectly transferred to the foundation of the column and so as not todamage the mechanism whereby the bar is moved.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of the specificembodiment when read in connection with the accompanying drawings, inwhich Figure 1 is a side viewlof my drill bit reshap-' ing mechanism,-

Figure 2 is a perspective view of a typical drill bit of the typereshaped'in my. device,

- Figure 3 is a plan'view of a female die employed in my invention, 7

Figurel is an enlarged fragmentary sectional View through the female dieof Figure 3 and the upper end of its supportingcolumn,

Figure 5 is a vertical sectional view through the male and female dieand showing a portion of the cam follower employed in my device,

- Figure 6 is a fragmentary vertical sectional view taken on line 6-6 ofFigure 1, r

, Figure '7 is a fragmentary sectional View taken on line 1-1 of Figure6. a

a A ,drillreshaping mechanism, to overcome the defect hereinbeforeenumerated, must have at least two totally distinct characteristics; itmust be capable of performing the reshaping opera-v tion with speed andease, and it also must provide means for protecting the threaded skirtof, the drill bit while reshaping pressure is applied to the drillbit. 77

Accordingly, .a preferred embodiment of my invention,=referring toFigures 1 and 2 of the drawings, is constituted by a mechanism whichincludeszthe foundation foot I0 having rising thereabove'zthe column I2which terminates in an upper capital or head M, in which is formed thesocket l5. =:On either sidethe base H! has. a pairof upstanding lugsor'ears l6 which are drilled at 18 for the reception of bolts tosecurelyattach the deviceto a suitablefo-undation or base. The column l2has an axial bore 20 which communicates with the cam receiving slot 22near the foot of the column. Laterally through the base is opening orslot 24 which inter sects the axisof thecolumn. Mounted in the slot24'is the cam shaft which has secured thereto the cam 28 that isattached by means of set screws 30, or in any other suitable manner. Thecam has a cup 29 in a portion of its face and also includes the wedgeface 3|. In Figure 7 the cup 29 is set so that its lowest point inrelation to its axis of rotation is in line with the axial bore 20 ofthe column.

Each end of the cam shaft 26 is supported in the journals 34 which arehere shown to be vertically adjustable. Each side of the journals has atongue 35 which fits into guideways 36 formed in the bracket 38. Roughlythe bracket 38 is U-shaped and in its lower portion a screw 40 isthreaded to press against the under side of the journal for variablepositioning of the journal vertically. A look nut 42 on each of thescrews 40 is employed to secure the bolt or screw in its adjustedposition. Secured to one end of the shaft 26 is the lever 48 which isemployed to rotate the shaft and which has the foot pedal 50 on itsouter end. In the drawings the key 52 is employed to secure the lever tothe shaft 26. A spring 54 biases the lever upwardly and at one end thespring has a hook engaged in the opening 56 in the lever shank and atits other end a similar hook engages in an opening of the bracket 60 onthe column l2. An adjustable stop screw 62 mounted in the lug. 64 on thelever [presses between the lever and a portion of the column to maintainthe lever in a predetermined raised position, so that the cam when atrest will lie as desired.

Mounted in the axial bore of the column is the cam follower bar 68 whichhas a lower rounded face that rests against the cam and on its upper endthe boss 12 that is adapted to be inserted into the threaded skirt of adetachable drill lblt. A female die block is fitted into the seat H: onthe upper end of the column and is indicated by the numeral [4. The diehas a central aperture to accommodate the upper end of rod 68 and itsboss. The female die is so formed and shaped that by its contours itwill receive and shape a heated drill bit which is presented theretowith force, and in a manner to support the wings of the drill bitagainst distortion.

The length of the boss. 12 is somewhat greater than the depth of thethreaded skirt of the drill bit so that when a drill bit as 18 is on theboss it will be supported as shown in Figure 5, in such a manner thatthe skirt does not receive longitudinal pressure. The bit 18 has aplurality of radial wings 86 which have an outside gauge diametersomewhat greater than the diameter of the skirt of the bit and whichtherefore are buttressed as indicated at 82. In sharpening such a drillbit which has become dulled it is important not only to replace andrenew the sharp or cutting edges of the wings 80, but also to return the\bit to its original gauge diameter or as near to that as is possible,so that such gauge diameter as has been lost by wear will not. bepermitted to detract from the usefulness of the .bit in subsequentdrillin operations. The male die 90 is so shaped as to conform. to thedesired finished contour of a reshaped bit, and includes a centering pinor boss 96 which serves to engage the drill bit being sharpened at itscenter water hole 98 or by the usual depression at this point. The pin96 prevents the inward movement of; metal during the swaging operationand also insures, in those cases where the bit has a central hole, thatthe water hole is not reduced or closed.

It will be understood that means are employed for bringing the male andfemale dies together with force to reshape a drill bit placed in thefemale die. It is preferable, according to my method of operation, tomove the male memfber, although it will be obvious that movement couldbe imparted to the female member and the cam follower' against a fixedor approaching male member and the same result obtained.

Method of operation According to my method of operation, a drill bit isheated to a proper forging temperature and is then placed in the femaledie 14, so that the buttresses of the wings rest on the slopingshoulders I06 in the die block and support those wings. The boss 12 willbe adjusted vertically so that it enters the threaded skirt of the drillbit and supports the head of the bit upon which the wings and teeth arebeing formed and because of its length being greater than the depth ofthe socket of the bit no pressure can be applied to the threaded skirt.The male die, in the case where it is the movable element, is broughtinto contact with the face of the bit and into association with thefemale member with force, so that the heated metal will be pressed andswaged to the configuration of the dies. The metal of the wings will beswaged outwardly and will also be provided with a cutting edge. When theforging operation is complete, and the operator wishes to remove theforged drill bit from the female die, he applies pressure to the lever48', usually with his foot, and against the force of spring 54 to rotatethe cam shaft 26 and to cause the wedge or cam portion 3| to beinterposed under the rounded end of the cam follower bar 68. This willextrude the drill from its seat in the female die. g 7

It is to be noted that during the forging operation. some force isapplied to the cam follower along its longitudinal axis. This force isthen transferred to the cam at its lowest point and in a manner thatavoids applying it to the shaft off centerv but directly axial of thecam shaft. This can be seen in Figure '7. This force is then transferredlaterally to the journal 34 and thence to the frame or base of thecolumn. When it is necessary to adjust the height of the boss,v ratherthan doing so by readjusting the relation of the camto the cam follower,the camshaft and cam are raised or lowered. vertically throughadjustment of the bearings in. their supporting guides without changingthe desired relation between the camand cam follower. In this way nounusual stresses or strains are applied to the cam shaft or the cam tothe cam follower bar.

Although I have shown andv described certain specificembodiments of myinvention, I am fully aware; that many modifications thereof arepossible. My invent-ion,v therefore, is not to be restricted, exceptinsofaras is necessitated by the prior art and by the spirit of theappended claims.

I claim:

1. In a drill bit reshaping. mechanism in which a bit is pressed into afemale die and a member is pressed against the bit to extrude it fromthe die following the shaping. operation, means for supporting andmoving said member comprising: a shaft journaled for rotation laterallyof the axis of the bit to be pressed, means for rotating said shaft onoccasion, a cam on said shaft on the axis of said bit to !be pressed anda cam follower bar between said cam and the boss, said cam having acupped'face adapted to receive an end of said cam follower bar in amanner to transfer force applied thereto directly to the rotatable shaftand its journals.

2. A reshaping mechanism for detachable drill bits of the type havingwinged teeth on the cutting face and a threaded skirt therebehind, whichmechanism comprises: a column having lower journals on either end of alateral passage, said column also having an axial passage intersectingsaid lateral passage, a shaft in said journals, means for rotating saidshaft on occasion, a cam on said shaft having a cupped face directedupwardly when the cam is in the at rest position and including a camwedge to one side of its axis of rotation, a cam follower bar slidablymovable in the axial passage of said column and including an upper boss,a female die on said column and having a central aperture for thereception of the boss on the cam follower bar, and a male die to press abit in said female die to reshape the same.

3. A reshaping mechanism for dulled detachable drill bits of the typehaving a threaded skirt, which mechanism comprises: a female die shapedto receive and support the wings of a bit to be sharpened, a male die topress the winged face of a drill bit in said female die to shape thecutting edges and swage the drill Wings radially outward, a boss in saidfemale die to support the bit in a manner to prevent the force of thepressing operation upon the winged face being applied to the threadedskirt of the drill bit, and means for forcing said boss outward in saidfemale die to extrude a sharpened bit following the forming operation.

4; In a detachable drill bit reshaping mechani'sm in which the bit beingsharpened has a threaded skirt and is pressed into a femal die, a bossto fit into the threaded skirt of the bit 15 being sharpened to supportthe bit during the re-

